EP1528839B1 - Induction heating cooker and method for operating the same - Google Patents
Induction heating cooker and method for operating the same Download PDFInfo
- Publication number
- EP1528839B1 EP1528839B1 EP04022523A EP04022523A EP1528839B1 EP 1528839 B1 EP1528839 B1 EP 1528839B1 EP 04022523 A EP04022523 A EP 04022523A EP 04022523 A EP04022523 A EP 04022523A EP 1528839 B1 EP1528839 B1 EP 1528839B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- voltage
- magnetic
- cooking container
- induction heating
- heating cooker
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Lifetime
Links
- 238000010438 heat treatment Methods 0.000 title claims description 63
- 230000006698 induction Effects 0.000 title claims description 57
- 238000000034 method Methods 0.000 title claims description 8
- 239000000463 material Substances 0.000 claims description 99
- 238000010411 cooking Methods 0.000 claims description 95
- 239000003990 capacitor Substances 0.000 claims description 33
- 239000012611 container material Substances 0.000 claims description 33
- 238000009499 grossing Methods 0.000 claims description 13
- 239000000696 magnetic material Substances 0.000 claims description 8
- 238000001514 detection method Methods 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 4
- 230000003213 activating effect Effects 0.000 claims description 3
- 238000010586 diagram Methods 0.000 description 8
- 238000004519 manufacturing process Methods 0.000 description 3
- 230000008859 change Effects 0.000 description 2
- 230000009467 reduction Effects 0.000 description 2
- 230000006872 improvement Effects 0.000 description 1
- 230000001939 inductive effect Effects 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 229910000859 α-Fe Inorganic materials 0.000 description 1
Images
Classifications
-
- A—HUMAN NECESSITIES
- A47—FURNITURE; DOMESTIC ARTICLES OR APPLIANCES; COFFEE MILLS; SPICE MILLS; SUCTION CLEANERS IN GENERAL
- A47J—KITCHEN EQUIPMENT; COFFEE MILLS; SPICE MILLS; APPARATUS FOR MAKING BEVERAGES
- A47J27/00—Cooking-vessels
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05B—ELECTRIC HEATING; ELECTRIC LIGHT SOURCES NOT OTHERWISE PROVIDED FOR; CIRCUIT ARRANGEMENTS FOR ELECTRIC LIGHT SOURCES, IN GENERAL
- H05B6/00—Heating by electric, magnetic or electromagnetic fields
- H05B6/02—Induction heating
- H05B6/06—Control, e.g. of temperature, of power
- H05B6/062—Control, e.g. of temperature, of power for cooking plates or the like
Definitions
- the present invention relates to an induction heating cooker and a method for operating the same, and more particularly to an induction heating cooker which includes a container material discriminating unit capable of accurately discriminating whether the material of a cooking container placed in the induction heating cooker is magnetic or non-magnetic, based on a phase change in a resonant capacitor voltage of an inverter circuit caused by a difference between resonance characteristics of a magnetic load and resonance characteristics of a non-magnetic load, and a method for operating the induction heating cooker.
- FIG. 1 is a block diagram illustrating configurations of an inverter circuit and a container material discriminating unit included in the conventional induction heating cooker.
- the induction heating cooker includes an inverter circuit for generating a magnetic field by causing current to flow through a coil in accordance with a switching operation of a switch element, and inducing the magnetic field into a cooking container placed in the induction heating cooker, thereby generating eddy current to heat the cooking container.
- the inverter circuit includes an AC power source adapted to supply a general AC voltage, a rectifier adapted to rectify the AC voltage supplied from the AC power source, a filter adapted to filter the rectified voltage outputted from the rectifier, and a switching unit adapted to perform a switching operation in response to the filtered voltage outputted from the filter, thereby applying a high-power, high-frequency voltage to the coil.
- Such a conventional induction heating cooker also includes a container material discriminating unit.
- This container material discriminating unit will be described in detail with reference to FIG. 1 .
- the container material discriminating unit includes a current detecting unit 1 adapted to detect current flowing through the coil of the inverter circuit, and a voltage comparing unit 2 adapted to compare a DC voltage outputted from the current detecting unit 1 with a reference voltage, which is a divided voltage obtained by two resistors.
- the current detecting unit 1 includes a current detector, a diode, and a capacitor.
- the current detector detects high-frequency sine wave current components from current flowing through the coil of the inverter circuit.
- the detected current is rectified and smoothed by the diode and capacitor, so that a DC voltage is outputted from the current detecting unit 1.
- the DC voltage outputted from the current detecting unit 1 is inputted to the voltage comparing unit 2.
- the DC voltage is compared with a reference voltage, which has a predetermined voltage level for discrimination of a magnetic or non-magnetic load.
- the voltage comparing unit 2 determines that the cooking container is a magnetic load, and generates a corresponding discrimination signal.
- the voltage comparing unit 2 determines that the cooking container is a non-magnetic load, and generates a corresponding discrimination signal.
- the discrimination signal generated from the voltage comparing unit 2 is applied to a microcomputer 3.
- the microcomputer 3 determines, based on the discrimination signal, that the cooking container is a magnetic load, it activates the inverter circuit to heat the cooking container.
- the microcomputer 3 determines that the cooking container is a non-magnetic load, it does not activate the inverter circuit, and controls the cooker to operate appropriately.
- the above-mentioned conventional container material discriminating unit has problems.
- the voltage comparing unit 2 which discriminates the material of the cooking container, may operate erroneously.
- the induction heating cooker may operate erroneously.
- the present invention has been made in view of the above-mentioned problems incurred in the related art, and an object of the invention is to provide an induction heating cooker which includes a container material discriminating unit capable of accurately discriminating whether the material of a cooking container placed in the induction heating cooker is magnetic or non-magnetic, using a phase change in a resonant capacitor voltage of an inverter circuit and a switching pulse signal of the inverter circuit, irrespective of the load of the cooking container, and a method for operating the induction heating cooker.
- the present invention provides an induction heating cooker comprising: a power supply for rectifying an AC voltage, filtering the rectified voltage, and supplying the filtered voltage as an input voltage of the induction heating cooker; an inverter circuit for heating a cooking container placed in the induction heating cooker, using the voltage supplied from the power supply; and a container material discriminating unit for discriminating whether a material of the cooking container is magnetic or non-magnetic, based on a resonant capacitor voltage of the inverter circuit and a switching pulse signal of the inverter circuit, upon an initial operation of the induction heating cooker, whereby the cooking container is selectively heated in accordance with the result of the discrimination.
- the container material discriminating unit may comprise: a voltage detecting unit for detecting the resonant capacitor voltage of the inverter circuit, half-wave rectifying the detected voltage, dividing the half-wave-rectified voltage, and outputting the divided voltage as the result of the detection; and a logic determining unit for comparing the voltage outputted from the voltage detecting unit with the switching pulse signal of the inverter circuit, thereby outputting a pulse signal having a pulse width varying depending on whether the material of the cooking container is magnetic or non-magnetic.
- the container material discriminating unit may further comprise: a DC voltage smoothing unit for converting the pulse signal outputted from the logic determining unit into a DC voltage; and a microcomputer for determining, based on the DC voltage, whether the material of the cooking container is magnetic or non-magnetic, and controlling the inverter circuit, based on the result of the determination.
- the logic determining unit may comprise an AND gate for outputting a pulse signal having a pulse width varying in accordance with a variation in load depending on the material of the cooking container such that the pulse width of the pulse signal varies within a range from 1/4 to 1/2 of a period of the switching pulse signal when the material of the cooking material is magnetic, while varying within a range from 0 to 1/4 of the period of the switching pulse signal when the material of the cooking material is non-magnetic.
- the microcomputer may comprise: a magnetic material determining unit for comparing the DC voltage outputted from the DC voltage smoothing unit with a reference value, thereby determining that the material of the cooking container is magnetic when the DC voltage is not less than 1/4 of the control voltage source(Vce), while determining that the material of the cooking container is non-magnetic when the DC voltage is less than 1/4 of the control voltage source(Vce); and an inverter controller for activating the inverter circuit when it is determined that the material of the cooking container is magnetic, so as to heat the cooking container.
- the present invention provides a method for operating an induction heating cooker, comprising the steps of: A) operating an inverter circuit included in the induction heating cooker upon an initial operation of the induction heating cooker; B) outputting, as a material discriminating signal, a pulse signal having a pulse width varying depending on a material of a cooking container placed in the induction heating cooker, based on a resonant capacitor voltage of the inverter circuit and a switching pulse signal of the inverter circuit; C) determining whether the material of the cooking container is magnetic or non-magnetic, based on the material discriminating signal outputted at the step B); and D) operating the inverter circuit when it is determined at the step C) that the material of the cooking container is magnetic, thereby heating the cooking container.
- the step C) may comprise the steps of: converting the pulse signal outputted at the step B) into a DC voltage; comparing the DC voltage with a predetermined reference value; determining that the material of the cooking container is magnetic when the DC voltage has a level not less than 25% of the control voltage source(Vce); and determining that the material of the cooking container is non-magnetic when the DC voltage has a level less than 25% of the control voltage source(Vce).
- FIG. 2 is a block diagram illustrating the configuration of a container material discriminating unit included in the induction heating cooker according to the present invention.
- FIG. 3 is a graph depicting the waveform of current flowing through a coil included in an inverter circuit according to the present invention, and the waveform of a resonant capacitor voltage according to the present invention.
- FIG. 4 is a waveform diagram of signals generated in association with operation of the container material discriminating unit according to the present invention.
- FIG. 5 is a circuit diagram illustrating a detailed configuration of the container material discriminating unit according to the present invention.
- FIG. 6 is a flow chart illustrating an operation of the container material discriminating unit in the induction heating cooker according to the present invention.
- the induction heating cooker of the present invention includes a power supply adapted to supply a DC voltage.
- the power supply includes a rectifier (not shown) for rectifying a general AC voltage, thereby producing a DC voltage, and a filter (not shown) for filtering the rectified voltage.
- the induction heating cooker also includes an inverter circuit 20 for heating a cooking container placed in the induction heating cooker, using the voltage supplied from the power supply.
- the induction heating cooker of the present invention further includes a container material discriminating unit 10 for discriminating whether the material of a cooking container placed in the induction heating cooker is magnetic or non-magnetic, based on a resonant capacitor voltage of the inverter circuit 20, and a switching pulse signal of the inverter circuit 20, so as to control the heating operation of the induction heating cooker.
- a container material discriminating unit 10 for discriminating whether the material of a cooking container placed in the induction heating cooker is magnetic or non-magnetic, based on a resonant capacitor voltage of the inverter circuit 20, and a switching pulse signal of the inverter circuit 20, so as to control the heating operation of the induction heating cooker.
- the container material discriminating unit 10 includes a logic determining unit 12 for comparing the resonant capacitor voltage of the inverter circuit 20 with the switching pulse signal of the inverter circuit 20, thereby outputting a pulse signal having a pulse width determined depending on the material of the cooking container.
- the container material discriminating unit 10 also includes a voltage detecting unit 11.
- the voltage detecting unit 11 detects the resonant capacitor voltage of the inverter circuit 20, half-wave rectifies the detected voltage, divides the half-wave-rectified voltage, and outputs the resultant voltage to the logic determining unit 12.
- the container material discriminating unit 10 further includes a DC voltage smoothing unit 13 for converting the pulse signal outputted from the logic determining unit 12 into a DC voltage, and a microcomputer 14 for determining, based on the DC voltage, whether the material of the cooking container is magnetic or non-magnetic, and controlling the inverter circuit 20, based on the result of the determination.
- the voltage detecting unit 11 is electrically connected to the inverter circuit 20 to detect the resonant capacitor voltage of the inverter circuit 20.
- the voltage detecting unit 11 half-wave rectifies the detected voltage, divides the half-wave-rectified voltage, and outputs the resultant voltage to the logic determining unit 12.
- the container material discriminating unit 10 utilizes characteristics of a resonance frequency varying depending on a variation in the load according to a variation in the material of the cooking container, in order to discriminate the material of the cooking container. That is, the voltage detecting unit 11 detects the resonant capacitor voltage of the inverter circuit 20, and sends a voltage signal indicative of the result of the detection to the logic determining unit 12. The voltage signal outputted from the voltage detecting unit 11 has a particular phase corresponding to the material of the cooking container, so that it is possible to determine the material of the cooking container, based on a variation in the phase of the voltage signal.
- the logic determining unit 12 receives the voltage signal outputted from the voltage detecting unit 11 and the switching pulse signal of the inverter circuit 20, and compares the received signals, thereby outputting a material discriminating signal.
- the material discriminating signal has a pulse width varying depending on the material of the cooking container within respective phase variation ranges of the switching pulse signal and resonance capacitor voltage.
- the DC voltage smoothing unit 13 receives the material discriminating signal from the logic determining unit 12, and outputs the material discriminating signal in the form of a smooth DC voltage.
- the DC voltage from the DC voltage smoothing unit 13 is applied to the microcomputer 14. Based on the DC voltage applied thereto, the microcomputer 14 determines whether the material of the cooking container is magnetic or non-magnetic. Based on the result of the determination, the microcomputer 14 controls the inverter circuit 20.
- the microcomputer 14 includes a magnetic material determining unit 14a for comparing the DC voltage outputted from the DC voltage smoothing unit 13 with a reference value stored in the magnetic material determining unit 14a, thereby determining whether the material of the cooking container is magnetic or non-magnetic, and an inverter controller 14b for activating the inverter circuit 20 when it is determined that the material of the cooking container is magnetic, so as to heat the cooking container.
- the magnetic material determining unit 14a determines that the material of the cooking container is magnetic. If not, the magnetic material determining unit 14a determines that the material of the cooking container is non-magnetic.
- the waveform of current flowing through the coil of the inverter circuit 20 and the waveform of the resonant capacitor voltage of the inverter circuit 20 exhibit a variation in phase depending on the material of the cooking container. That is, different phases are exhibited in accordance with whether the material of the cooking container is magnetic or non-magnetic, as indicated by waveforms Sg1 and Sg2, respectively.
- the current I wc flowing through the coil exhibits different phases when the material of the cooking container is magnetic (Sg1) and when the material of the cooking container is non-magnetic (Sg2), respectively.
- the resonant capacitor voltage V c which has a phase difference of 90° from the coil current, exhibits different phases when the material of the cooking container is magnetic (Sg1) and when the material of the cooking container is non-magnetic (Sg2), respectively.
- the coil current and resonant capacitor voltage have different phases, respectively.
- the voltage detecting unit 11 detects the resonant capacitor voltage V c , and outputs a voltage signal indicative of the result of the detection.
- the material of the cooking container is determined, using the phase variation characteristics of the resonant capacitor voltage V c depending on the material of the cooking container.
- the logic determining unit 12 compares the voltage signal outputted from the voltage detecting unit 11 with the switching pulse signal of the inverter circuit 20, and outputs a material discriminating signal, which is a pulse signal. As shown in FIG. 4 , the voltage signal has a level varying depending on whether the material of the cooking material is magnetic or non-magnetic, as indicated by waveforms Sg3 and Sg4.
- the logic determining unit 12 logically ANDs the output voltage signal of the voltage detecting unit 11 and the switching pulse signal of the inverter circuit 20, thereby outputting a pulse signal.
- the pulse signal outputted from the logic determining unit 12 is set to have a pulse width ranging from 1/4 to 1/2 of the period of the switching pulse signal when the material of the cooking material is magnetic (Sg3).
- the pulse signal is set to have a pulse width ranging from 0 to 1/4 of the period of the switching pulse signal.
- the material discriminating signal outputted from the logic determining unit 12 has a pulse width varying depending on whether the material of the cooking container is magnetic or non-magnetic. As shown in FIG. 4 , the logic determining unit 12 outputs a pulse signal P3 when the material of the cooking container is magnetic (Sg3), while outputting a pulse signal P4 when the material of the cooking container is non-magnetic.
- the voltage detecting unit 11 includes a diode, a capacitor and a plurality of resistors. In the illustrated case, two resistors, that is, first and second resistors R1 and R2, are used.
- the voltage detecting unit 11 detects the voltage of the resonant capacitor included in the inverter circuit 20, half-wave rectifies the detected voltage, divides the half-wave-rectified voltage, and outputs the resultant voltage to the logic determining unit 12. The voltage division is carried out in accordance with the resistance ratio between the first and second resistors R1 and R2.
- the logic determining unit 12 includes an AND gate.
- the AND gate receives the output voltage signal from the voltage detecting unit 11 and the switching pulse signal of the inverter circuit 20, and compares the received signals.
- the AND gate outputs a material discriminating signal having a pulse width varying depending on whether the material of the cooking container is magnetic or non-magnetic.
- the pulse width of the material discriminating signal outputted from the logic determining unit 12 is variable within respective phase variation ranges of the switching pulse signal and resonance capacitor voltage in accordance with the present invention. Accordingly, it is possible to output a signal having a pulse width varying depending on the material of the cooking container, irrespective of a variation in the load of the cooking container.
- the DC voltage smoothing unit 13 includes a low pass filter consisting of a resistor and a capacitor. With this configuration, the DC voltage smoothing unit 13 filters the material discriminating signal outputted from the logic determining unit 12, thereby outputting a smooth DC voltage.
- FIG. 6 is a flow chart illustrating the operation sequence of the container material discriminating unit.
- the induction heating cooker receives an input DC voltage from the power supply, which rectifies and filters an input AC voltage. By the input DC voltage, the inverter circuit 20 is operated (S1).
- a resonant capacitor voltage generated in accordance with the operation of the inverter circuit 20 is detected by the voltage detecting unit 11.
- the detected resonant capacitor voltage is sine-wave rectified.
- the rectified voltage is divided by the resistors of the voltage detecting unit 11 in accordance with the resistance ratio between the resistors.
- the divided voltage is outputted (S2).
- the divided voltage is applied to the AND gate of the logic determining unit 12, along with the switching pulse signal of the inverter circuit 20, so that the applied signals are compared (S3).
- the AND gate outputs, as a material discriminating signal, a pulse signal having a pulse width corresponding to 1/4 to 1/2 of the period of the switching pulse signal.
- the AND gate outputs, as a material discriminating signal, a pulse signal having a pulse width corresponding to 0 to 1/2 of the period of the switching pulse signal.
- the material discriminating signal passes through the low pass filter of the DC voltage smoothing unit 13, which consists of one resistor and one capacitor, so that the material discriminating signal is outputted in the form of a smooth DC voltage (S4).
- the smooth DC voltage is applied to the microcomputer 14, which in turn compares the DC voltage with a reference value stored in the microcomputer 14 (S5).
- the microcomputer 14 determines that the material of the cooking container is magnetic (S6). If not, the microcomputer 14 determines that the material of the cooking container is non-magnetic (S7).
- the inverter circuit 20 When it is determined that the material of the cooking container is magnetic, the inverter circuit 20 is operated to heat the cooking container. On the other hand, when it is determined that the material of the cooking container is non-magnetic, the inverter circuit 20 is not operated.
- the induction heating cooker having the above-described configuration according to the present invention can accurately discriminate the material of the cooking container, irrespective of the load of the cooking container. That is, it is possible to prevent the induction heating cooker from operating erroneously due to an erroneous determination of the container material discriminating unit as to the material of the cooking container, which may occur at the boundary of the load between a load value corresponding to the magnetic material and a load value corresponding to the non-magnetic material.
- the induction heating cooker includes the container material discriminating unit, which is adapted to discriminate whether the material of the cooking container is magnetic or non-magnetic, it is possible to use a simple voltage detector, without using an expensive current detector.
- the logic determining unit can also be implemented using a general logic element, that is, an AND gate. Accordingly, a great reduction in manufacturing costs is achieved.
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Food Science & Technology (AREA)
- Induction Heating Cooking Devices (AREA)
- Cookers (AREA)
- Inverter Devices (AREA)
Description
- The present invention relates to an induction heating cooker and a method for operating the same, and more particularly to an induction heating cooker which includes a container material discriminating unit capable of accurately discriminating whether the material of a cooking container placed in the induction heating cooker is magnetic or non-magnetic, based on a phase change in a resonant capacitor voltage of an inverter circuit caused by a difference between resonance characteristics of a magnetic load and resonance characteristics of a non-magnetic load, and a method for operating the induction heating cooker.
- An example of a conventional induction heating cooker is illustrated. The configuration of the conventional induction heating cooker and problems incurred therein will be described below with reference to
FIG. 1. FIG. 1 is a block diagram illustrating configurations of an inverter circuit and a container material discriminating unit included in the conventional induction heating cooker. - The induction heating cooker includes an inverter circuit for generating a magnetic field by causing current to flow through a coil in accordance with a switching operation of a switch element, and inducing the magnetic field into a cooking container placed in the induction heating cooker, thereby generating eddy current to heat the cooking container.
- The inverter circuit includes an AC power source adapted to supply a general AC voltage, a rectifier adapted to rectify the AC voltage supplied from the AC power source, a filter adapted to filter the rectified voltage outputted from the rectifier, and a switching unit adapted to perform a switching operation in response to the filtered voltage outputted from the filter, thereby applying a high-power, high-frequency voltage to the coil.
- Such a conventional induction heating cooker also includes a container material discriminating unit. This container material discriminating unit will be described in detail with reference to
FIG. 1 . The container material discriminating unit includes acurrent detecting unit 1 adapted to detect current flowing through the coil of the inverter circuit, and avoltage comparing unit 2 adapted to compare a DC voltage outputted from thecurrent detecting unit 1 with a reference voltage, which is a divided voltage obtained by two resistors. - The current detecting
unit 1 includes a current detector, a diode, and a capacitor. The current detector detects high-frequency sine wave current components from current flowing through the coil of the inverter circuit. The detected current is rectified and smoothed by the diode and capacitor, so that a DC voltage is outputted from the current detectingunit 1. - The DC voltage outputted from the
current detecting unit 1 is inputted to thevoltage comparing unit 2. In the voltagelevel comparing unit 2, the DC voltage is compared with a reference voltage, which has a predetermined voltage level for discrimination of a magnetic or non-magnetic load. When the DC voltage is less than the reference voltage, thevoltage comparing unit 2 determines that the cooking container is a magnetic load, and generates a corresponding discrimination signal. On the other hand, when the DC voltage is more than the reference voltage, thevoltage comparing unit 2 determines that the cooking container is a non-magnetic load, and generates a corresponding discrimination signal. - The discrimination signal generated from the
voltage comparing unit 2 is applied to amicrocomputer 3. When themicrocomputer 3 determines, based on the discrimination signal, that the cooking container is a magnetic load, it activates the inverter circuit to heat the cooking container. On the other hand, when themicrocomputer 3 determines that the cooking container is a non-magnetic load, it does not activate the inverter circuit, and controls the cooker to operate appropriately. - However, the above-mentioned conventional container material discriminating unit has problems. For example, when the DC voltage indicative of the value of the current detected by the current detecting
unit 1 has a level equal to or approximate to the reference voltage, thevoltage comparing unit 2, which discriminates the material of the cooking container, may operate erroneously. In this case, the induction heating cooker may operate erroneously. - In order to detect the high-frequency coil current generated from the inverter circuit, it is necessary to use an expensive current detector, which is made of a ferrite material. For this reason, there is an increase in manufacturing costs.
- The object is solved by the features of the independent claims.
- The present invention has been made in view of the above-mentioned problems incurred in the related art, and an object of the invention is to provide an induction heating cooker which includes a container material discriminating unit capable of accurately discriminating whether the material of a cooking container placed in the induction heating cooker is magnetic or non-magnetic, using a phase change in a resonant capacitor voltage of an inverter circuit and a switching pulse signal of the inverter circuit, irrespective of the load of the cooking container, and a method for operating the induction heating cooker.
- In accordance with one aspect, the present invention provides an induction heating cooker comprising: a power supply for rectifying an AC voltage, filtering the rectified voltage, and supplying the filtered voltage as an input voltage of the induction heating cooker; an inverter circuit for heating a cooking container placed in the induction heating cooker, using the voltage supplied from the power supply; and a container material discriminating unit for discriminating whether a material of the cooking container is magnetic or non-magnetic, based on a resonant capacitor voltage of the inverter circuit and a switching pulse signal of the inverter circuit, upon an initial operation of the induction heating cooker, whereby the cooking container is selectively heated in accordance with the result of the discrimination.
- The container material discriminating unit may comprise: a voltage detecting unit for detecting the resonant capacitor voltage of the inverter circuit, half-wave rectifying the detected voltage, dividing the half-wave-rectified voltage, and outputting the divided voltage as the result of the detection; and a logic determining unit for comparing the voltage outputted from the voltage detecting unit with the switching pulse signal of the inverter circuit, thereby outputting a pulse signal having a pulse width varying depending on whether the material of the cooking container is magnetic or non-magnetic.
- The container material discriminating unit may further comprise: a DC voltage smoothing unit for converting the pulse signal outputted from the logic determining unit into a DC voltage; and a microcomputer for determining, based on the DC voltage, whether the material of the cooking container is magnetic or non-magnetic, and controlling the inverter circuit, based on the result of the determination.
- The logic determining unit may comprise an AND gate for outputting a pulse signal having a pulse width varying in accordance with a variation in load depending on the material of the cooking container such that the pulse width of the pulse signal varies within a range from 1/4 to 1/2 of a period of the switching pulse signal when the material of the cooking material is magnetic, while varying within a range from 0 to 1/4 of the period of the switching pulse signal when the material of the cooking material is non-magnetic.
- The microcomputer may comprise: a magnetic material determining unit for comparing the DC voltage outputted from the DC voltage smoothing unit with a reference value, thereby determining that the material of the cooking container is magnetic when the DC voltage is not less than 1/4 of the control voltage source(Vce), while determining that the material of the cooking container is non-magnetic when the DC voltage is less than 1/4 of the control voltage source(Vce); and an inverter controller for activating the inverter circuit when it is determined that the material of the cooking container is magnetic, so as to heat the cooking container.
- In accordance with another aspect, the present invention provides a method for operating an induction heating cooker, comprising the steps of: A) operating an inverter circuit included in the induction heating cooker upon an initial operation of the induction heating cooker; B) outputting, as a material discriminating signal, a pulse signal having a pulse width varying depending on a material of a cooking container placed in the induction heating cooker, based on a resonant capacitor voltage of the inverter circuit and a switching pulse signal of the inverter circuit; C) determining whether the material of the cooking container is magnetic or non-magnetic, based on the material discriminating signal outputted at the step B); and D) operating the inverter circuit when it is determined at the step C) that the material of the cooking container is magnetic, thereby heating the cooking container.
- The step C) may comprise the steps of: converting the pulse signal outputted at the step B) into a DC voltage; comparing the DC voltage with a predetermined reference value; determining that the material of the cooking container is magnetic when the DC voltage has a level not less than 25% of the control voltage source(Vce); and determining that the material of the cooking container is non-magnetic when the DC voltage has a level less than 25% of the control voltage source(Vce).
- In accordance with the present invention, it is possible to accurately discriminate the material of the cooking container, irrespective of the load of the cooking container. Thus, it is possible to prevent the induction heating cooker from operating erroneously due to an erroneous determination of the container material discriminating unit as to the material of the cooking container.
- The above objects, and other features and advantages of the present invention will become more apparent after reading the following detailed description when taken in conjunction with the drawings, in which:
-
FIG. 1 is a block diagram illustrating configurations of an inverter circuit and a container material discriminating unit included in a conventional induction heating cooker; -
FIG. 2 is a block diagram illustrating the configuration of a container material discriminating unit included in an induction heating cooker according to the present invention; -
FIG. 3 is a graph depicting the waveform of current flowing through a coil included in an inverter circuit according to the present invention, and the waveform of a resonant capacitor voltage according to the present invention; -
FIG. 4 is a waveform diagram of signals generated in association with operation of the container material discriminating unit according to the present invention; -
FIG. 5 is a circuit diagram illustrating a detailed configuration of the container material discriminating unit according to the present invention; and -
FIG. 6 is a flow chart illustrating an operation of the container material discriminating unit in the induction heating cooker according to the present invention. - Now, embodiments of an induction heating cooker according to the present invention will be described in detail with reference to the annexed drawings.
- Although there may be various embodiments associated with the induction heating cooker according to the present invention, the following description will be given in conjunction with the most preferred embodiment.
-
FIG. 2 is a block diagram illustrating the configuration of a container material discriminating unit included in the induction heating cooker according to the present invention.FIG. 3 is a graph depicting the waveform of current flowing through a coil included in an inverter circuit according to the present invention, and the waveform of a resonant capacitor voltage according to the present invention.FIG. 4 is a waveform diagram of signals generated in association with operation of the container material discriminating unit according to the present invention.FIG. 5 is a circuit diagram illustrating a detailed configuration of the container material discriminating unit according to the present invention.FIG. 6 is a flow chart illustrating an operation of the container material discriminating unit in the induction heating cooker according to the present invention. - The induction heating cooker of the present invention includes a power supply adapted to supply a DC voltage. The power supply includes a rectifier (not shown) for rectifying a general AC voltage, thereby producing a DC voltage, and a filter (not shown) for filtering the rectified voltage. The induction heating cooker also includes an
inverter circuit 20 for heating a cooking container placed in the induction heating cooker, using the voltage supplied from the power supply. - In particular, the induction heating cooker of the present invention further includes a container material
discriminating unit 10 for discriminating whether the material of a cooking container placed in the induction heating cooker is magnetic or non-magnetic, based on a resonant capacitor voltage of theinverter circuit 20, and a switching pulse signal of theinverter circuit 20, so as to control the heating operation of the induction heating cooker. - As shown in
FIG. 2 , the container materialdiscriminating unit 10 includes alogic determining unit 12 for comparing the resonant capacitor voltage of theinverter circuit 20 with the switching pulse signal of theinverter circuit 20, thereby outputting a pulse signal having a pulse width determined depending on the material of the cooking container. - The container material
discriminating unit 10 also includes avoltage detecting unit 11. Thevoltage detecting unit 11 detects the resonant capacitor voltage of theinverter circuit 20, half-wave rectifies the detected voltage, divides the half-wave-rectified voltage, and outputs the resultant voltage to thelogic determining unit 12. The container materialdiscriminating unit 10 further includes a DCvoltage smoothing unit 13 for converting the pulse signal outputted from thelogic determining unit 12 into a DC voltage, and amicrocomputer 14 for determining, based on the DC voltage, whether the material of the cooking container is magnetic or non-magnetic, and controlling theinverter circuit 20, based on the result of the determination. - The
voltage detecting unit 11 is electrically connected to theinverter circuit 20 to detect the resonant capacitor voltage of theinverter circuit 20. Thevoltage detecting unit 11 half-wave rectifies the detected voltage, divides the half-wave-rectified voltage, and outputs the resultant voltage to thelogic determining unit 12. - In particular, the container
material discriminating unit 10 utilizes characteristics of a resonance frequency varying depending on a variation in the load according to a variation in the material of the cooking container, in order to discriminate the material of the cooking container. That is, thevoltage detecting unit 11 detects the resonant capacitor voltage of theinverter circuit 20, and sends a voltage signal indicative of the result of the detection to thelogic determining unit 12. The voltage signal outputted from thevoltage detecting unit 11 has a particular phase corresponding to the material of the cooking container, so that it is possible to determine the material of the cooking container, based on a variation in the phase of the voltage signal. - The
logic determining unit 12 receives the voltage signal outputted from thevoltage detecting unit 11 and the switching pulse signal of theinverter circuit 20, and compares the received signals, thereby outputting a material discriminating signal. The material discriminating signal has a pulse width varying depending on the material of the cooking container within respective phase variation ranges of the switching pulse signal and resonance capacitor voltage. - The DC
voltage smoothing unit 13 receives the material discriminating signal from thelogic determining unit 12, and outputs the material discriminating signal in the form of a smooth DC voltage. The DC voltage from the DCvoltage smoothing unit 13 is applied to themicrocomputer 14. Based on the DC voltage applied thereto, themicrocomputer 14 determines whether the material of the cooking container is magnetic or non-magnetic. Based on the result of the determination, themicrocomputer 14 controls theinverter circuit 20. - The
microcomputer 14 includes a magneticmaterial determining unit 14a for comparing the DC voltage outputted from the DCvoltage smoothing unit 13 with a reference value stored in the magneticmaterial determining unit 14a, thereby determining whether the material of the cooking container is magnetic or non-magnetic, and aninverter controller 14b for activating theinverter circuit 20 when it is determined that the material of the cooking container is magnetic, so as to heat the cooking container. - If the DC voltage is not less than 1/4 of the control voltage source(Vce), the magnetic
material determining unit 14a determines that the material of the cooking container is magnetic. If not, the magneticmaterial determining unit 14a determines that the material of the cooking container is non-magnetic. - As shown in
FIG. 3 , the waveform of current flowing through the coil of theinverter circuit 20 and the waveform of the resonant capacitor voltage of theinverter circuit 20 exhibit a variation in phase depending on the material of the cooking container. That is, different phases are exhibited in accordance with whether the material of the cooking container is magnetic or non-magnetic, as indicated by waveforms Sg1 and Sg2, respectively. - That is, the current Iwc flowing through the coil exhibits different phases when the material of the cooking container is magnetic (Sg1) and when the material of the cooking container is non-magnetic (Sg2), respectively. Similarly, the resonant capacitor voltage Vc, which has a phase difference of 90° from the coil current, exhibits different phases when the material of the cooking container is magnetic (Sg1) and when the material of the cooking container is non-magnetic (Sg2), respectively.
- The coil current and resonant capacitor voltage have different phases, respectively. The
voltage detecting unit 11 detects the resonant capacitor voltage Vc, and outputs a voltage signal indicative of the result of the detection. In accordance with the present invention, the material of the cooking container is determined, using the phase variation characteristics of the resonant capacitor voltage Vc depending on the material of the cooking container. - The
logic determining unit 12 compares the voltage signal outputted from thevoltage detecting unit 11 with the switching pulse signal of theinverter circuit 20, and outputs a material discriminating signal, which is a pulse signal. As shown inFIG. 4 , the voltage signal has a level varying depending on whether the material of the cooking material is magnetic or non-magnetic, as indicated by waveforms Sg3 and Sg4. - The
logic determining unit 12 logically ANDs the output voltage signal of thevoltage detecting unit 11 and the switching pulse signal of theinverter circuit 20, thereby outputting a pulse signal. The pulse signal outputted from thelogic determining unit 12 is set to have a pulse width ranging from 1/4 to 1/2 of the period of the switching pulse signal when the material of the cooking material is magnetic (Sg3). When the material of the cooking material is non-magnetic (Sg4), the pulse signal is set to have a pulse width ranging from 0 to 1/4 of the period of the switching pulse signal. - Thus, the material discriminating signal outputted from the
logic determining unit 12 has a pulse width varying depending on whether the material of the cooking container is magnetic or non-magnetic. As shown inFIG. 4 , thelogic determining unit 12 outputs a pulse signal P3 when the material of the cooking container is magnetic (Sg3), while outputting a pulse signal P4 when the material of the cooking container is non-magnetic. - Hereinafter, the configuration of the container
material discriminating unit 10 will be described in more detail with reference toFIG. 5 . - The
voltage detecting unit 11 includes a diode, a capacitor and a plurality of resistors. In the illustrated case, two resistors, that is, first and second resistors R1 and R2, are used. Thevoltage detecting unit 11 detects the voltage of the resonant capacitor included in theinverter circuit 20, half-wave rectifies the detected voltage, divides the half-wave-rectified voltage, and outputs the resultant voltage to thelogic determining unit 12. The voltage division is carried out in accordance with the resistance ratio between the first and second resistors R1 and R2. - The
logic determining unit 12 includes an AND gate. The AND gate receives the output voltage signal from thevoltage detecting unit 11 and the switching pulse signal of theinverter circuit 20, and compares the received signals. Thus, the AND gate outputs a material discriminating signal having a pulse width varying depending on whether the material of the cooking container is magnetic or non-magnetic. - In this case, the pulse width of the material discriminating signal outputted from the
logic determining unit 12 is variable within respective phase variation ranges of the switching pulse signal and resonance capacitor voltage in accordance with the present invention. Accordingly, it is possible to output a signal having a pulse width varying depending on the material of the cooking container, irrespective of a variation in the load of the cooking container. - The DC
voltage smoothing unit 13 includes a low pass filter consisting of a resistor and a capacitor. With this configuration, the DCvoltage smoothing unit 13 filters the material discriminating signal outputted from thelogic determining unit 12, thereby outputting a smooth DC voltage. - Operation of the induction heating cooker having the above-described configuration according to the present invention will be described with reference to
FIG. 6 , which is a flow chart illustrating the operation sequence of the container material discriminating unit. - The induction heating cooker receives an input DC voltage from the power supply, which rectifies and filters an input AC voltage. By the input DC voltage, the
inverter circuit 20 is operated (S1). - Thereafter, a resonant capacitor voltage generated in accordance with the operation of the
inverter circuit 20 is detected by thevoltage detecting unit 11. The detected resonant capacitor voltage is sine-wave rectified. The rectified voltage is divided by the resistors of thevoltage detecting unit 11 in accordance with the resistance ratio between the resistors. The divided voltage is outputted (S2). - The divided voltage is applied to the AND gate of the
logic determining unit 12, along with the switching pulse signal of theinverter circuit 20, so that the applied signals are compared (S3). - Where the material of the cooking container is magnetic, the AND gate outputs, as a material discriminating signal, a pulse signal having a pulse width corresponding to 1/4 to 1/2 of the period of the switching pulse signal. On the other hand, where the material of the cooking container is non-magnetic, the AND gate outputs, as a material discriminating signal, a pulse signal having a pulse width corresponding to 0 to 1/2 of the period of the switching pulse signal.
- The material discriminating signal passes through the low pass filter of the DC
voltage smoothing unit 13, which consists of one resistor and one capacitor, so that the material discriminating signal is outputted in the form of a smooth DC voltage (S4). - The smooth DC voltage is applied to the
microcomputer 14, which in turn compares the DC voltage with a reference value stored in the microcomputer 14 (S5). - If the DC voltage has a level corresponding to 25% or more of the control voltage source(Vce), the
microcomputer 14 determines that the material of the cooking container is magnetic (S6). If not, themicrocomputer 14 determines that the material of the cooking container is non-magnetic (S7). - When it is determined that the material of the cooking container is magnetic, the
inverter circuit 20 is operated to heat the cooking container. On the other hand, when it is determined that the material of the cooking container is non-magnetic, theinverter circuit 20 is not operated. - As apparent from the above description, the induction heating cooker having the above-described configuration according to the present invention can accurately discriminate the material of the cooking container, irrespective of the load of the cooking container. That is, it is possible to prevent the induction heating cooker from operating erroneously due to an erroneous determination of the container material discriminating unit as to the material of the cooking container, which may occur at the boundary of the load between a load value corresponding to the magnetic material and a load value corresponding to the non-magnetic material.
- Since the induction heating cooker includes the container material discriminating unit, which is adapted to discriminate whether the material of the cooking container is magnetic or non-magnetic, it is possible to use a simple voltage detector, without using an expensive current detector. The logic determining unit can also be implemented using a general logic element, that is, an AND gate. Accordingly, a great reduction in manufacturing costs is achieved.
- In accordance with the reduction in manufacturing costs achieved using a simple logic configuration, there are an enhancement in the reliability of products and an improvement in price competitiveness.
Claims (11)
- An induction heating cooker comprising:a power supply for rectifying an AC voltage, filtering the rectified voltage, and supplying the filtered voltage as an input voltage of the induction heating cooker;an inverter circuit (20) for heating a cooking container placed in the induction heating cooker upon an initial operation of the induction heating cooker using the voltage supplied from the power supply; anda container material discriminating unit (10) for discriminating whether a material of the cooking container is magnetic or non-magnetic, whereby the cooking container is selectively heated in accordance with the result of the discrimination, characterized in that the container material discriminating unit (10) includes a voltage detecting unit (11) and a logic determining unit (12), wherein the voltage detecting unit (11) is adapted to detect a resonant capacitor voltage (Vc) of the inverter circuit (20), wherein the resonant capacitor voltage (Vc) having different phases depending on the material of the cooking container, wherein the logic determining unit (12) is adapted to logically combine the voltage outputted by the voltage detecting unit (11) with a switching pulse signal of the inverter circuit (20), thereby outputting a pulse signal (P3, P4) having a pulse width varying depending on whether the material of the cooking container is magnetic or non-magnetic.
- The induction heating cooker according to claim 1, wherein the container material discriminating unit (10) comprises:the voltage detecting unit (11) for detecting the resonant capacitor voltage of the inverter circuit (20), half-wave rectifying the detected voltage, dividing the half-wave-rectified voltage, and outputting the divided voltage as the result of the detection.
- The induction heating cooker according to claim 2, wherein the container material discriminating unit (10) further comprises:a DC voltage smoothing unit (13) for converting the pulse signal outputted from the logic determining unit (12) into a DC voltage; anda microcomputer (14) for determining, based on the DC voltage, whether the material of the cooking container is magnetic or non-magnetic, and controlling the inverter circuit (20), based on the result of the determination.
- The induction heating cooker according to claim 2, wherein the logic determining unit (12) comprises an AND gate for outputting a pulse signal having a pulse width varying in accordance with a variation in load depending on the material of the cooking container such that the pulse width of the pulse signal varies within a range from 1/4 to 1/2 of a period of the switching pulse signal when the material of the cooking material is magnetic, while varying within a range from 0 to 1 /4 of the period of the switching pulse signal when the material of the cooking material is non-magnetic.
- The induction heating cooker according to claim 2, wherein the voltage detecting unit (11) comprises a plurality of resistors for dividing a voltage applied thereto in accordance with a resistance ratio thereof.
- The induction heating cooker according to claim 3, wherein the DC voltage smoothing unit (13) comprises a low pass filter for smoothing the pulse signal received from the logic determining unit (12) in the form of a DC voltage.
- The induction heating cooker according to claim 3, wherein the microcomputer (14) comprises:a magnetic material determining unit (14a) for comparing the DC voltage outputted from the DC voltage smoothing unit (13) with a reference value, thereby determining that the material of the cooking container is magnetic when the DC voltage is not less than 1/4 of the control voltage source (Vce), while determining that the material of the cooking container is non-magnetic when the DC voltage is less than 1 /4 of the control voltage source (Vce); andan inverter controller (14b) for activating the inverter circuit (20) when it is determined that the material of the cooking container is magnetic, so as to heat the cooking container.
- The induction heating cooker according to claim 1, wherein the power supply comprises:a power source for supplying a general AC voltage;a rectifier for rectifying the AC voltage: anda filter for filtering the rectified voltage.
- A method for operating an induction heating cooker, comprising the steps of:A) operating an inverter circuit (20) included in the induction heating cooker upon an initial operation of the induction heating cooker;
characterized by the steps of:B) detecting a resonant capacitor voltage (Vc) of the inverter circuit (20) and outputting a signal based on the detection, wherein the resonant capacitor voltage (Vc) having different phases depending on the material of the cooking container,
logical combining the signal based on the detection with a switching pulse signal of the inverter circuit (20);
outputting based on the result of the logical combination, as a material discriminating signal, a pulse signal (P3, P4) having a pulse width varying depending on a material of a cooking container placed in the induction heating cooker,C) determining whether the material of the cooking container is magnetic or non-magnetic, based on the material discriminating signal outputted at the step B); andD) operating the inverter circuit (20) when it is determined at the step C) that the material of the cooking container is magnetic, thereby heating the cooking container. - The method according to claim 9, wherein the step B) comprises the steps of:detecting the resonant capacitor voltage of the inverter circuit(20);sine-wave rectifying the detected voltage;dividing the rectified voltage, comparing the divided voltage with the switching pulse signal of the inverter circuit (20); andoutputting the result of the comparison as the material discriminating signal.
- The method according to claim 9, wherein the step C) comprises the steps of:converting the pulse signal outputted at the step B) into a DC voltage;comparing the DC voltage with a predetermined reference value;determining that the material of the cooking container is magnetic when the DC voltage has a level not less than 25% of the control voltage source (Vce); anddetermining that the material of the cooking container is non-magnetic when the DC voltage has a level less than 25% of the control voltage source (Vce).
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
KR2003075068 | 2003-10-27 | ||
KR10-2003-0075068A KR100529925B1 (en) | 2003-10-27 | 2003-10-27 | Induction heating rice cooker and its method for the same |
Publications (2)
Publication Number | Publication Date |
---|---|
EP1528839A1 EP1528839A1 (en) | 2005-05-04 |
EP1528839B1 true EP1528839B1 (en) | 2010-01-13 |
Family
ID=34420669
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP04022523A Expired - Lifetime EP1528839B1 (en) | 2003-10-27 | 2004-09-22 | Induction heating cooker and method for operating the same |
Country Status (6)
Country | Link |
---|---|
US (1) | US6936799B2 (en) |
EP (1) | EP1528839B1 (en) |
JP (1) | JP2005129539A (en) |
KR (1) | KR100529925B1 (en) |
CN (1) | CN1612646A (en) |
DE (1) | DE602004025074D1 (en) |
Families Citing this family (19)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
KR100746406B1 (en) * | 2006-02-10 | 2007-08-03 | 쿠쿠전자주식회사 | Cooking controlling apparatus for electric pressure heat insulting rice cooker |
KR100746407B1 (en) * | 2006-02-10 | 2007-08-03 | 쿠쿠전자주식회사 | Cooking controlling apparatus for electric pressure heat insulting rice cooker |
JP4909662B2 (en) * | 2006-07-12 | 2012-04-04 | 日立アプライアンス株式会社 | Electromagnetic induction heating device |
KR20090048789A (en) * | 2007-11-12 | 2009-05-15 | 삼성전자주식회사 | Induction heating cooker |
KR20090057495A (en) * | 2007-12-03 | 2009-06-08 | 삼성전자주식회사 | Induction heating cooker and control method therof |
ES2351293B1 (en) * | 2009-03-11 | 2011-11-21 | Bsh Electrodomesticos España, S.A. | INDUCTION HEATING AND PROCEDURE APPARATUS FOR YOUR OPERATION. |
US20120061381A1 (en) * | 2009-06-01 | 2012-03-15 | Panasonic Corporation | Induction cooking device |
RU2453977C2 (en) * | 2009-07-24 | 2012-06-20 | Общество с ограниченной ответственностью "Силовая электроника" | Control method for stand-alone inverter with resonance switching |
KR100977639B1 (en) * | 2010-02-11 | 2010-08-23 | 주식회사 윌링스 | Inductive heater having a intelligent judging function for normal load detecting and driving method thereof |
DE102010027833A1 (en) * | 2010-04-15 | 2011-10-20 | E.G.O. Elektro-Gerätebau GmbH | Cooking vessel, heater and cooking system |
CH703021B1 (en) * | 2010-04-30 | 2014-11-14 | Inducs Ag | Circuit arrangement for an induction cooking appliance process for operating the circuit arrangement for an induction cooking appliance. |
KR101408265B1 (en) * | 2011-04-22 | 2014-06-17 | 린나이코리아 주식회사 | Cooking method in a rice cooker |
CN103746576A (en) * | 2014-01-10 | 2014-04-23 | 美的集团股份有限公司 | Power supply circuit, control circuit for heating device and heating device |
KR102629987B1 (en) * | 2016-09-01 | 2024-01-29 | 삼성전자주식회사 | Cooking apparatus and method for controlling the same |
CN108873761B (en) * | 2017-05-10 | 2021-07-27 | 佛山市顺德区美的电热电器制造有限公司 | Heating control method and device of induction cooker |
US10993292B2 (en) | 2017-10-23 | 2021-04-27 | Whirlpool Corporation | System and method for tuning an induction circuit |
EP3534673B1 (en) * | 2018-03-02 | 2021-09-15 | Electrolux Appliances Aktiebolag | Induction hob and method for operating an induction hob |
CN108571752B (en) * | 2018-04-10 | 2020-11-03 | 佛山市众拓科技有限公司 | Single coil electromagnetic oven capable of simultaneously using heat radiation energy and electromagnetic induction energy |
CN112394244B (en) * | 2019-08-19 | 2021-09-14 | 广东美的白色家电技术创新中心有限公司 | Detection circuit, electric appliance and control method |
Family Cites Families (6)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3775577A (en) * | 1972-04-20 | 1973-11-27 | Environment One Corp | Induction cooking apparatus having pan safety control |
JP2893750B2 (en) * | 1989-09-28 | 1999-05-24 | 松下電器産業株式会社 | Induction heating cooker |
US5648008A (en) * | 1994-11-23 | 1997-07-15 | Maytag Corporation | Inductive cooking range and cooktop |
GB9701066D0 (en) * | 1997-01-20 | 1997-03-12 | Induced Energy Ltd | Induction heating apparatus |
ES2254327T3 (en) * | 2001-11-21 | 2006-06-16 | Matsushita Electric Industrial Co., Ltd. | INDUCTION HEATING DEVICE. |
US6894255B2 (en) * | 2002-03-22 | 2005-05-17 | Matsushita Electric Industrial Co., Ltd. | Induction heating apparatus |
-
2003
- 2003-10-27 KR KR10-2003-0075068A patent/KR100529925B1/en not_active IP Right Cessation
-
2004
- 2004-09-22 DE DE602004025074T patent/DE602004025074D1/en not_active Expired - Lifetime
- 2004-09-22 EP EP04022523A patent/EP1528839B1/en not_active Expired - Lifetime
- 2004-10-04 US US10/956,024 patent/US6936799B2/en not_active Expired - Fee Related
- 2004-10-21 CN CNA2004100882145A patent/CN1612646A/en active Pending
- 2004-10-25 JP JP2004309564A patent/JP2005129539A/en active Pending
Also Published As
Publication number | Publication date |
---|---|
KR100529925B1 (en) | 2005-11-22 |
EP1528839A1 (en) | 2005-05-04 |
US6936799B2 (en) | 2005-08-30 |
DE602004025074D1 (en) | 2010-03-04 |
CN1612646A (en) | 2005-05-04 |
KR20050039970A (en) | 2005-05-03 |
US20050087526A1 (en) | 2005-04-28 |
JP2005129539A (en) | 2005-05-19 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
EP1528839B1 (en) | Induction heating cooker and method for operating the same | |
CN107801264B (en) | Cooking apparatus and control method thereof | |
KR102172415B1 (en) | Induction heating device and pot detecting method thereof | |
EP3651548B1 (en) | Single pulse pre-test method for improving vessel detection accuracy | |
US5424514A (en) | Apparatus for sensing small object in high-frequency induction heating cooker | |
KR20060036740A (en) | Induction heating cooker to limit the power level when input voltage is low and its operating method therefor | |
EP1592285A1 (en) | Apparatus for controlling inverter circuit of induction heat cooker | |
JPH0495383A (en) | Induction heating cooker | |
JP2000023830A (en) | Electromagnetic induction heating rice cooker and its manufacture | |
KR100241449B1 (en) | Apparatus and method for judging small load of induction heating cooker | |
KR19990058482A (en) | Driving device of induction heating cooker and its driving method | |
KR100186481B1 (en) | Power control apparatus for induction cooker | |
KR102153499B1 (en) | Heating device and power control method | |
KR100230775B1 (en) | Heating control method for induction heating cooker | |
KR100239365B1 (en) | Load judgment and heating method for induction heating cooker | |
JP5340026B2 (en) | Induction heating cooker | |
KR0141797B1 (en) | Switching element protection device for complex cooker | |
JPS6122436B2 (en) | ||
KR0138637B1 (en) | Detection device & method of microwave oven | |
EP3432683B1 (en) | Induction cooker, method of operation and computer program | |
JPH08148266A (en) | Induction heating cooker | |
KR100206832B1 (en) | Switching element protection circuit for induction cooker | |
KR100206843B1 (en) | Heating control method for induction heating cooker | |
KR0162409B1 (en) | Induction heating cooker | |
JP3175576B2 (en) | Induction heating cooker |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
PUAI | Public reference made under article 153(3) epc to a published international application that has entered the european phase |
Free format text: ORIGINAL CODE: 0009012 |
|
17P | Request for examination filed |
Effective date: 20040922 |
|
AK | Designated contracting states |
Kind code of ref document: A1 Designated state(s): AT BE BG CH CY CZ DE DK EE ES FI FR GB GR HU IE IT LI LU MC NL PL PT RO SE SI SK TR |
|
AX | Request for extension of the european patent |
Extension state: AL HR LT LV MK |
|
AKX | Designation fees paid |
Designated state(s): DE FR GB |
|
17Q | First examination report despatched |
Effective date: 20060126 |
|
GRAP | Despatch of communication of intention to grant a patent |
Free format text: ORIGINAL CODE: EPIDOSNIGR1 |
|
GRAS | Grant fee paid |
Free format text: ORIGINAL CODE: EPIDOSNIGR3 |
|
GRAA | (expected) grant |
Free format text: ORIGINAL CODE: 0009210 |
|
AK | Designated contracting states |
Kind code of ref document: B1 Designated state(s): DE FR GB |
|
REG | Reference to a national code |
Ref country code: GB Ref legal event code: FG4D |
|
REF | Corresponds to: |
Ref document number: 602004025074 Country of ref document: DE Date of ref document: 20100304 Kind code of ref document: P |
|
PLBE | No opposition filed within time limit |
Free format text: ORIGINAL CODE: 0009261 |
|
STAA | Information on the status of an ep patent application or granted ep patent |
Free format text: STATUS: NO OPPOSITION FILED WITHIN TIME LIMIT |
|
26N | No opposition filed |
Effective date: 20101014 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: PLFP Year of fee payment: 13 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: PLFP Year of fee payment: 14 |
|
REG | Reference to a national code |
Ref country code: FR Ref legal event code: PLFP Year of fee payment: 15 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: FR Payment date: 20190806 Year of fee payment: 16 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: GB Payment date: 20190806 Year of fee payment: 16 |
|
PGFP | Annual fee paid to national office [announced via postgrant information from national office to epo] |
Ref country code: DE Payment date: 20200806 Year of fee payment: 17 |
|
GBPC | Gb: european patent ceased through non-payment of renewal fee |
Effective date: 20200922 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: FR Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20200930 |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: GB Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20200922 |
|
REG | Reference to a national code |
Ref country code: DE Ref legal event code: R119 Ref document number: 602004025074 Country of ref document: DE |
|
PG25 | Lapsed in a contracting state [announced via postgrant information from national office to epo] |
Ref country code: DE Free format text: LAPSE BECAUSE OF NON-PAYMENT OF DUE FEES Effective date: 20220401 |